Dyeing of cellulose acetate with acid dyes in an aqueous solution containing a mixture of swelling agents



Patented Aug. 8 1950 DYEING or osLLULosE. ACETATE: WITH. Acne nyns IN AN AQUEOUS SOLUTION CONTAINING A MIXTURE. or SWELLDIG AGENTS Jackson A. Woodruff, St. Davids, Pa., assignor-to American Viscose Corporation, Wilmington, bet, a corporation of Delaware No Drawing. Application April 16, 1946,

Serial No. 662,624

16 Claims.

The present invention. relates to an improved method of dyeing cellulose acetate, and to dyebath compositions suitable for carrying out the dyeing method.

Two general methods are available and widely practiced for dyeing cellulose acetate from aqueous solutions of the acid dyestufis, namely the alcohol assistant method, and the acid assistan method. In accordance with the first mentioned method, the dyeing is carried out in the presence of an alcohol, such as ethyl, methyl, or isopropyl alcohol, etc, dissolved in the aqueous solution of the acid dyestuii, while in accordance with the second method, the dyeing is effected in the presence of a mixture of organic and inorganic acids dissolved in, the aqueous dyebath.

Of these two methods, the alcohol assistant. method has the advantage of producing dyeings of superior wash-fiastness, while the acid assistant method is more economical.

In the case of both the alcohol and acid assistants, the assistants have to be present in the bath in high concentration before their favorable efiects on the dyeings obtained are noticeable, which greatly increases the cost of the dyeing operation, For instance, in the case of methyl, ethyl, or isopropyl alcohol, the alcohol has to be present in the bath in concentrations of 60% or more by volume, it deep wash-fast dyeings areto be obtained. The acid assistants must also. be present in high concentrations of greater than and approaching the critical concentration at which de-lustering of the cellulose acetate by the acid takes place under normal conditions of dyeing as respects concentration of the dye, time, and temperature. For instance, in the case where the acid assistant consists of a mixture of formic, acetic, and sulfuric acids, each of the acids has to be present in the bath in a concentration of 8.3% by weight, making a total acid concentration of about 5%, which is much higher than is desirable for economical, commercial practice. Further, although satisfactory dyeings on cellulose acetate from aqueous solutions of the acid dyestufis, containing as dyeing assistant, a mixture of formic, acetic, and sulfuric acids may be obtained, the use of the noxious formic and acetic acids in the open machines preferred by the dyers is prohibited and special apparatus is required for carrying out the dyeing process.

The present dyeing method involves a modification of the aforementioned conventional dyeing procedures whereby all of the advantages of the: alcohol assistant method and the acid assistant method are obtained using aqueous dyebathscontaining the acid dyes in normal concentration and an alcohol or acid dyeing assistant in a concentration of less than /2 that previously required. i l

I find that when small amounts of certain hydroxy derivatives ofbenzene or of poly-hydrobenzene are dissolved in. aqueous solutions; of the acid dyestufis, the concentration of alcohol or ci p m dyein as i t nt i h hammer of shade desired, the dyeings obtained with the dyebaths containing small amounts of resorcinol phloroglucinol, or cyclohexanol, and materially reduced amounts of alcohol or acid assistants), are equivalent in all respects to the, dyeings, ob: tained from baths containing th alcohol or. acid,

assistants in the higher concentrations, and,

which do not. contain the. resorcinol, phloroglu cinol, or cyclohexanol.

The following examples. will illustrate the,

process, of the present invention in. comparison with conventional procedures.

Example I A fabric formed from yarns of c llul e acetate was immersed for ei h minut .a .dylebath,

onsisti f water.-30%. ethyl alc h l. byv lume.

and 3% rescrcinol. by wei ht. and hayin dissolved therein about 9.8%. o Br l i nt Wool Blue.

L (Color Ind xNo. 5 .3 The mp ature or. the bath was F. The fabric was then withdrawn, partially dried, and washed in a 1% aqueous soap solution, after which it was rinsed and dried.

A sample of the same cellulose acetate iabri'c was dyed, under exactly the same conditions,

ferent baths e fou d t :be dyed t substam tially the same deep blue shade, and the dyeings showed equivalent fastness during the scouring step.

Example II A cellulose acetate fabric was immersed in a dyebath consisting of water, 3% sulfuric acid by weight, and 2.5% of resorcinol, by weight, and having dissolved therein about .25% of Orange II (Color Index No.151). The fabric was immersed in the bath at a temperature of 90 F.; the temperature then was gradually raised over a period of about one-half hour to 120 F., and held at 120 F. for hour. The fabric was then rinsed, washed in a 1% aqueous soap solution, again rinsed, and dried.

A sample of the same fabric was dyed under identical conditions of temperature and immersion time but from a bath consisting of the dyestulf, water, and about 8 acetic acid, 8 formic acid and 8 sulfuric acid, by weight.

After dyeing, the fabrics were found to be dyed to substantially the same deep yelloworange color, and showed equivalent fastness to the scouring treatment.

Example III A cellulose acetate fabric was immersed in a d-yebath consisting of water, 1% resorcinol, by weight, and 2.2% sulfuric acid by weight, and having dissolved therein 0.2% of Anthralan Red BA (Color Index No. not listed) for one hour at a temperature of 175 F. The fabric was thereafter rinsed, washed with a 1% aqueous soap solution, rinsed and dried.

' The fabric was dyed to the same clear red shade, and had the same wash-fastness as a similar fabric dyed from an aqueous bath containing 8%;% acetic acid, il /3% formic acid, and 8 /3% sulfuric acid, by weight, under the conditions described in U. S. Patent No. 2,249,607.

The same results, as to similarity of shade and fastness to dyeing were obtained when two samples of cellulose acetate fabric were dyed from aqueous baths having compositions as described in Example II, but containing, as the acid dyestuff, about 2.5% of Fast Brown R (Color Index No. 175).

j The same results were also obtained when two samples of cellulose acetate fabric were dyed from aqueous baths having'compositions as described in Example II, but containing about 3.3% of cyclohexanol by volume, and'about 2% sulfuric acid, by weight.

Other acid dyestuffs which may be used are:

Color Index No.

Fast Silk Yellow G 145 Amido Yellow E. Pr 11 Alizarine Supra Blue A (Not listed) Artol Brown BL Artol Green GL Artol Red BL Croceine Orange Y 26 As will be observed, the presence of about 3% or less of resorcinol or cyclohexanol in the bath permits a reduction in the amount of ethyl alcohol assistant required for effective dyeing from 60% by volume to 30% by volume under the dyeing conditions described. The alcohol concentration may be reduced still further, in some cases and may range from about to about 30% by volume, depending upon the precise dyeing conditions, the lower concentrations being satisfactory, for instance, at somewhat higher temperatures of the bath. In the case of the acid assistant, as is apparent from Example 2, the presence of about 2.5% of resorcinol by weight in the bath permits a reduction in the amount of acid required from 25% by weight to only 3% by weight. Moreover, when the resoroinol is used, excellent dyeings are obtained from a bath containing the inorganic acid only as acid assistant. The possibility of eliminating the noxious formic and acetic acids is most unexpected and highly advantageous. The dyeings obtained from the baths containing resorcinol and sulfuric acid, in the indicated low concentrations, are in every way comparable with those obtained from baths containing a high .proportion of the mixed organic and inorganic acids, under the same dyeing conditions, and in the absence of the resorcinol.

As will be understood, the actual proportionate reduction in the amount of the alcohol or acid assistant required for satisfactory dyeings made possible by the presence of the resorcinol. phloroglucinol, or cyclohexanol will vary to some extent depending upon the dyeing conditions. In general, however, the dyebaths used in accordance with the invention will comprise an aqueous solution of the selected acid dyestuif containing a small amount of resorcinol, phloroglucinol, or cyclohexanol, and as primary dyeing assistant, a lower aliphatic alcohol or acids in an amount equal to less than about /2 the amount of such assistants required to dye cellulose acetate with the acid dyes from aqueous solution by conventional methods under normal conditions of dyeing as regards concentration of the dye, the period of dyeing and the temperature of the bath, and in the absence of the mentioned auxiliary assistants. The amount of resorcinol, phloroglucinol, or cyclohexanol will usually be from about 1 to 4%, but when phloroglucinol is used, it may be desirable to increase the concentration thereof in the bath to about 6%.

The mixture of alcohol or acid with resorcinol, phloroglucinol, or cyclohexanol is more strongly absorbed by the cellulose acetate fibers than is the alcohol or acid assistant alone. Exhaustion trials do not show any appreciable preferential absorption of the alcohol or acid, although the dye exhaustion is approximately 60-80%. It appears that the cellulose acetate fiber-alcohol or acid mixture with resorcinol, phloroglucinol, or cyclohexanol has a greater solvent power for the dye than a cellulose acetate fiber-alcohol or acid system, permitting more rapid and thorough diffusion of the dye through the structure.

That the use of resorcinol, phloroglucinol, or cyclohexanol in combination with the reduced amounts of alcohols or acids as primary dyeing assistants involves a different mechanism or phenomenon in relation to the dyeing of cellulose actate from aqueous solutions of acid dyestuffs, as compared to the alcohols or acid assistants alone, is evidenced by the different effect which the media have on the physical structure of the cellulose acetate when they are used in excess. If the poly-hydroxy-benzene or hydroxy hexahydro-benzene is not present, and the dyebath contains an excessive amount of alcohol or acid assistant, that is an amount in excess of the critical concentration which causes delustering, the cellulose acetate structure undergoes marked shrinkage or contraction, whereas when the polyhydroxy-benzene or hydroxy-hexa-hydro-benzene is present, and the alcohol or acid concentration an mist is in exces's o'f'the delustering concentration, the cellulose structure expands and is elongated.

"Whatever may be the precise explanation for the remarkable effects or small amounts of resorcinol, phloroglucinol, or cyclohexanol in combination with the conventional alcohol or "acid assistants, the dyeings obtained inaccordance with the present dyeing method compare favorably in all respects With the dyeings obtained from dyebaths in which the alcohol or acid dyeing assistants are used in high concentrations. The results are the more striking inasmuch as it has not been found possible to satisfactorily dye cellulose acetate from aqueous acid dye solutions containing resorcinol, phloroglucinol, or cyclohexanol only, in the absence of the primary dyeing assistant, even when the former are present in increased concentrations.

The invention has been described more particularly in connection with the use of resorcinol, phlorog lucinol, or cyclohexanol in combination withalcohols or acids as the primary dyeing assistants, since thealcohols andacids are most commonly used. However, I have also found that very beneficial results are obtained by the addition of a hydroxy benzene or hYdI'OXY-rPOlY- hydro-benzene as described herein to aqueous solutions of acid dyes containing, as primary dyeing assistants for cellulose acetate, substances other than the alcohols or acids, such as esters of the alcohols with lower fatty acids, of the type of butyl acetate, butyl formate, ethyl acetate, etc. as well as esters of the type of benzyl acetate. The amount of such esters required for the obtention of excellent dyeings on cellulose acetate from aqueous solutions of the acid dyes is also materially reduced when the bath contains resorcinol, phloroglucinol, or cyclohexanol in the previously stated low concentrations.

The cellulose acetate to be dyed may be in fabric form, in the form of packaged yarn, skeins, etc., or it may be in the form of films, sheets, or the like.

Variations and modifications may be made in carrying out the dyeing procedure described herein, and in the specific composition of the dye baths without departing from the spirit and scope of the invention as defined in the appended claims.

I claim:

1. Method of dyeing cellulose acetate with an acid dye com-prising the step of treating the acetate with an aqueous dyebath consisting of water, and acid dye, from to 35 volume percent of a lower aliphatic alcohol as primary dyeing assistant, and from 1 to 6 percent by weight of an auxiliary dyeing assistant selected from the group consisting of resorcinol, phloroglucinol, and cyclohexanol.

2. Method of dyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath containing an acid dye, an ester of an alcohol with an organic acid as primary dyeing assistant, and an auxiliary dyeing assistant selected from the group consisting of resorcinol, phloroglucinol, and cyclohexanol, the concentration of the ester in the bath being less than one-half the concentration thereof required to facilitate dyeing of the acetate with the acid dye from aqueous solution under corresponding dyeing conditions in the absence of the auxiliary assistant.

3. Method of dyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath containing an acid dye, an acid as primary dyeing =-assistant, and an auxiliary dyeing assistant selected from the group consisting of resorcinol, phloroglucinol, and cyclohexanol, the concentration of the acid dyeing assistant in the bath being less than onehalf the concentration thereof required to facilitate dyeing of the acetate with the acid dye from aqueous solution under corresponding dyeingconditions in the absenceof the'auxiliary dyeing assistant.

4. Method of dyeing cellulose acetate with-an acid dyecomprising the step of treating the acetate with an aqueous-dyebath consisting of water, an 'aciddye, from'lO to about"35% ethyl alcohol, by volume, andi'romabout J. to 3% of resorcinol by weight.

5. lvfethod ofdyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath consisting of water, an acid dye, about 30% ethyl alcohol'by volume, and from about 1 to 3% of resorcinol, by weight.

6. Methodof dyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath containing an acid dye, from about 2 to about 3.5% .sulfuric acid, by weight, and from about 1 to about'B% resorcinol, by weight.

7. Method of dyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath containing an acid dye, from about 10 to 35% ethyl alcohol by volume, and from about 1 to 6% phloroglucinol, by weight.

8. Method of dyeing cellulose acetate with an acid dye comprising the step of treating the acetate with an aqueous dyebath consisting of water, an acid dye, from about 10 to 35% ethyl alcohol and from about 1 to 4% cyclohexanol, by volume.

9. A dyebath for use in dyeing cellulose acetate with acid dyes and consisting of an aqueous solution of an acid dye containing from 10 to 35 volume percent of a lower aliphatic alcohol as a primary dyeing assistant and from 1 to 6 percent by weight of an auxiliary dyeing assistant selected from the group consisting of resorcinol, 'phloroglucinol, and cyclohexanol.

10. A composition for use in dyeing cellulose acetate with acid dyes comprising an aqueous solution of an acid dye, an ester of an alcohol with an organic acid as primary dyeing assistant and an auxiliary dyeing assistant selected from the group consisting of resorcinol, phloroglucinol, and cyclohexanol, the concentration of the ester in the solution being less than one-half the concentration thereof required to facilitate dyeing of the acetate with the acid dye from aqueous solution under corresponding dyeing conditions in the absence of the auxiliary dyeing assistant.

11. A composition for use in dyeing cellulose acetate With acid dyes comprising an aqueous solution of an acid dye containing an acid as a primary dyeing assistant, and an auxiliary dyeing assistant selected from the group consisting of resorcinol, phloroglucinol, and cyclohexanol;

the concentration of the acid primary dyeing assistant in the solution being less than one-half the concentration thereof required to facilitate dyeing of the acetate with the acid dye from aqueous solution under corresponding dyeinfg conditions in the absence of the auxiliary assistant.

12. A dyebath for use in dyeing cellulose acetate with acid dyes consisting of an aqueous solution of an acid dye containing from about 10% to about 35% ethyl alcohol, by volume, and from about 1 to about 3% resorcinol, by weight.

13. A dyebath for use in dyeing cellulose acetate with acid dyes consisting of an aqueous solution of an acid dye containing about 30% ethyl alcohol, by volume, and from about 1 to about 3% resorcinol, by weight. 14. A composition for use in dyeing cellulose acetate with acid dyes comprising an aqueous solution of an acid dye, containing from about 2 to 3.5% sulfuric acid, by weight, and from about 1 to 3% resorcinol by weight.

15. A composition for use in dyeing cellulose acetate with acid dyes comprising an aqueous solution of an acid dye, containing ethyl alcohol as a primary dyeing assistant and from about 1 to 6% by weight of phloroglucinol, the concentration of the primary dyeing assistant in the bath being less than one-half the concentration thereof required to facilitate dyeing of the acetate with the acid dye from aqueous solution under corresponding dyeing conditions and in the absence of the phloroglucinol.

16. A composition for use in dyeing cellulose acetate with acid dyes comprising an aqueous solution of an acid dye containing ethyl alcohol as a primary dyeing assistant and from about 1 to 4% by weight of cyclohexanol, the concenf tration of the primary dyeing assistant in the bath being less than one-half the concentration required to facilitate dyeing of the acetate with the acid dye from aqueous solution under normal dyeing conditions and in the absence of cyclohexanol.

JACKSON A. WOODRUFF.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,826,608 Ellis Oct. 6, 1931 1,984,788 Ellis Dec. 18, 1934 2,053,276 Ellis Sept. 8, 1936 2,120,552 Ellis June 14, 1938 2,182,964 Dreyfus Dec. 12, 1939 2,344,973 Croft Mar. 28, 1944 2,428,835 Croft Oct. 14, 1947 FOREIGN PATENTS Number Country Date 285,948 Great Britain Feb. 13, 1928 

1. METHOD OF DYEING CELLULOSE ACETATE WITH AN ACID DYE COMPRISING THE STEP OF TREATING THE ACETATE WITH AN AQUEOUS DYEBATH CONSISTING OF WATER, AND ACID DYE, FROM 10 TO 35 VOLUMEN PERCENT OF A LOWER ALIPHATIC ALCOHOL AS PRIMARY DYEING ASSISTANT, AND FROM 1 TO 6 PERCENT BY WEIGHT OF AN AUXILIARY DYEING ASSITANT SELECTED FROM THE GROUP CONSISTING OF RESORCINOL, PHLOROGLUCINOL, AND CYCLOHEXANOL.
 2. METHOD OF DYEING CELLULOSE ACETATE WITH AN ACID DYE COMPRISING THE STEP OF TRETING THE ACETATE WITH AN AQUEOUS DYEBATH CONTAINING AN ACID DYE, AN ESTER OF AN ALCOHOL WITH AN ORGANIC ACID AS PRIMARY DYEING ASSISTANT, AND AN AUXILIARY DYEING ASSISTANT SELECTED FROM THE GROUP CONSISTING OF RESORCINOL, PHLOROGLUCINOL, AND CYCLOHEXANOL, THE CONCENTRATION OF THE ESTER IN THE BATH BEING LESS THAN ONE-HALF THE CONCENTRATION THEREOF REQUIRED TO FACILITATE DYEING OF THE ACETATE WITH THE ACID DYE FROM AQUEOUS SOLUTION UNDER CORRESPONDING DYEING CONDITIONS IN THE ABSENCE OF THE AUXILIARY ASSISTANT.
 3. METHOD OF DYEING CELLULOSE ACETATE WITH AN ACID DYE COMPRISING THE STEP OF TREATING THE ACETATE WITH AN AQUEOUS DYEBATH CONTAINING AN ACID DYE, AND ACID AS PRIMARY DYEING ASSISTANT, AND AN AUXILIARY DYEING ASSITANT SELECTED FROM THE GROUP CONSISTING OF RESORCINOL, PHLOROGLUCINOL, AND CYCLOHEXANOL, THE CONCENTRATION OF THE ACID DYEING ASSISTANT IN THE BATH BEING LESS THAN ONEHALF THE CONCENTRATION THEREOF REQUIRED TO FACILITATE DYEING OF THE ACETATE WITH THE ACID DYE FROM AQUEOUS SOLUTION UNDER CORRESPONDING DYEING CONDITIONS IN THE ABSENCE OF THE AUXILIARY DYEING ASSISTANT. 